1. Field of the Invention
The present general inventive concept relates to an ink-jet print head, and more particularly, to a thermal transfer type ink-jet print head having a protective layer to protect a heat generation layer, and a method of fabricating the same.
2. Description of the Related Art
Conventionally, an ink-jet print heads may be classified into a piezoelectric type, which ejects ink using a piezoelectric member, and a heat transfer type, which ejects ink using bubbles generated when the ink is instantly heated by a heat generation member.
FIG. 1 shows a conventional heat transfer type ink-jet print head.
Referring to FIG. 1, a conventional ink-jet print head 100 comprises a heat generation layer 130, an electrode layer 140, a protective layer 160, which are laminated on a main substrate in this order, and a nozzle 195. Here, the heat generation layer 130 functions to instantly heat ink filled in an ink chamber 115, and the electrode layer 140 functions to apply electric power to the heat generation layer 130.
The protective layer 160 functions to protect the heat generation layer 130. Such a conventional protective layer 160 comprises a first protective layer 170 and a second protective layer 180 sequentially laminated on the top surfaces of the heat generation layer 130 and the electrode layer 140 as disclosed in U.S. Pat. No. 4,335,389. Here, the second protective layer 180 functions to prevent a failure of the heat generation layer 130, which is caused by cavitation force generated when bubbles formed within the ink chamber 115 are contracted after the ink is ejected. In general, the second protective layer 180 is formed by depositing tantalum (Ta) or tantalum nitride (TaNx) on the top surface of the first protective layer 170.
In addition, the first protective layer 170 functions to insulate the heat generation layer 130 and the electrode layer 140 and is formed by depositing any of silicon oxide (SiOx) silicon nitride (SiNx) on the top surfaces of the heat generation layer 130 and the electrode layer 140. The first protective layer 170 is generally formed by depositing SiNx, which is superior to SiOx in heat conductivity, on the top surfaces of the heat generation layer 130 and the electrode layer 140.
Meanwhile, a conventional first protective layer 170 formed as described above has defects such as fine holes usually called “pinholes,” which are formed at the time of forming the layer. In particular, these pinholes are inevitably formed due to characteristics of a process of forming such a protective layer and the material thereof. However, when the ink-jet print head 100 is used for a long time, the above-mentioned pinholes principally contribute to cause a failure of the first protective layer 170 due to cavitation force. Such a failure of the first protective layer 170 is more frequently produced at an area C where the heat generation layer 130 and the electrode layer 140 are joined to one another with a step being formed between them. As such, if the first protective layer 170 suffers a failure, a problem can be caused in that the heat generation layer 130 may also suffer a failure by cavitation force. In addition, the heat generation layer 130 may be electrically shorted with the second protective layer 180 or the ink may be filled in the ink chamber 115 through the damaged part of the first protective layer 170, whereby the heat generation layer 130 could also suffer a failure. As a result, the duration and/or quality of the ink-jet print head will be deteriorated.